Service Life Prediction of Lining Concrete of Subsea Tunnel under Combined Compressive Load and Carbonation

Qingdao Jiaozhou Bay subsea tunnel is the second self-built tunnel in China with the designed service life over 100 years.The durability of lining concrete are one of an important factors to determinate the service life of tunnel.Considering the main environmental loads and mechanical loads of subsea tunnel,the durability properties of lining concrete under combined action of compressive load and carbonation has been studied through the critical compressive load test,accelerated carbonation test,natural carbonation test and capillary suction test.The tests results show that critical compressive load apparently accelerates the carbonation and deteriorates the anti-permeability of concrete.Under the combined action of critical compressive load and carbonation,the durability of lining concrete decreases.Based on the carbonization life criteria and research results,for the high-performance concrete with proposed mix ratio,the predicted service life of lining concrete for Jiaozhou bay subsea tunnel is about 80 years which fails to reach the required service life.It is necessary to adopt other measurements simultaneously to improve the durability of lining concrete.

Durability of Lining Concrete of Subsea Tunnel under Combined Action of Freeze-thaw Cycle and Carbonation

Through the fast freeze-thaw cycle test,accelerated carbonation test,and natural carbonation test,the durability performance of lining concrete under combined action of freeze-thaw cycle and carbonation were studied.The experimental results indicate that freeze-thaw cycle apparently accelerates the process of concrete carbonation and carbonation deteriorates the freeze resistance of concrete.Under the combined action of freeze-thaw cycle and carbonation,the durability of lining concrete decreases.The carbonation depth of lining concrete at tunnel openings under freeze-thaw cycles and tunnel condition was predicted.For the high performance concrete with proposed mix ratio,the lining concrete tends to be unsafe because predicted carbonation depth exceeds the thickness of reinforced concrete protective coating.Adopting other measurements simultaneously to improve the durability of lining concrete at the tunnel openings is essential.

三臂凿岩台车施工技术在青岛胶州湾海底隧道中的应用研究

通过三臂液压凿岩台车在青岛胶州湾海底隧道施工中的应用研究,充分地发挥三臂液压凿岩台车作业范围大、灵活性强、空气粉尘污染小、安全文明、液压冲击钻高效的技术优势,不仅在Ⅱ,Ⅲ级围岩施工中体现了其无可比拟的优越性,而且在Ⅳ,Ⅴ级及破碎弱风化围岩施工中,也显示了其较强的适应性,实现了快速、优质、安全、高效施工。

青岛胶州湾海底隧道F_(4-4)含水断层注浆前后TSP探测分析

海底隧道含水断层的预报是海底隧道修建过程中的重大理论和技术难题之一,对其位置与规模的准确预报可为超前预注浆提供依据与指导.通过TSP超前探测,确定了青岛胶州湾海底隧道F4-4含水断层发育的位置与规模,探明了该断层受构造影响严重,围岩破碎,岩体强度低,自稳能力差,在极端地质条件下存在突水的高风险,施工风险极大.该预报为超前预注浆提供了依据,最后采用TSP手段对注浆后围岩情况进行了注浆效果检验,TSP探测结果表明,注浆后围岩整体性得到提高,其强度提高了19 .1 %,密度提高了3 .6 %,泊松比下降了7 .1 %,纵波波速增长了0 .8 %,纵横波比减小了7 .1 %,表明断层破碎带内含水量降低,裂隙得到有效充填,注浆效果显著,达到了注浆目的.该海底隧道含水断层的TSP超前预报方法以及注浆处理后的注浆效果检验手段对类似工程具有一定的借鉴与指导意义.

青岛胶州湾海底隧道涌水断层全断面帷幕注浆技术研究

青岛胶州湾海底隧道F_(4-4)断层破碎带,受构造影响严重,围岩破碎,岩体强度低,出水量大,拱顶自稳能力差,在极端地质条件下存在突水的高风险,施工风险极大.基于这种情况,通过现场试验确定了全断面帷幕注浆技术参数,主隧道注浆加固区范围为隧道开挖轮廓线外5m;上断面周边注浆扩散半径为1.5m,下断面注浆扩散半径为2m;注浆终孔间距为3.5m;水灰比为1:1的超细水泥;注浆压力为3～4MPa;施工工艺选用前进式注浆.最后采用全断面帷幕注浆技术方案和措施在青岛胶州湾海底隧道右线主洞穿越F_(4-4)断层的设计和施工中得到了成功的应用.通过检查孔检验,注浆效果良好,达到了开挖要求.全断面帷幕注浆技术对类似工程具有一定的借鉴与指导意义.